Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.244
Filtrar
1.
Environ Pollut ; 259: 113874, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32032982

RESUMO

Pieces of glass as solid wastes were recycled in the synthesis of highly order MCM-41 that decorated by green fabricated Co3O4 nanoparticles using the green extract of green tea leaves forming novel green nano-composite. The synthetic Co3O4/MCM-41 exhibit high surface area, low bandgap energy (1.63 eV), and typical spherical morphology decorated by Co3O4 nanoparticles. The composite was evaluated as green photocatalyst in effective oxidation of methyl parathion pesticide in the presence of a visible light source. The degradation results revealed complete removal of 50 mg/L and 100 mg/L after 60 min and 90 min, respectively using 0.25 of the catalyst at pH 8. The detection of the TOC in the treated methyl parathion solution gives strong indications about the formation of organic intermediate compounds during the oxidation steps. The main detected intermediate compound are C6H5OH(NO2), C6H5OH, (CH3O)3P(S), C6H4(OH)2, C6H3(OH)3, C6H4(NH2)OP(O)(OCH3)2, (CH3O)2P(O)OH, (CH2)2C(OH)OH(CHO)OC(O), and HO2C(CH2)2C(O)CHO. The detected intermediate compounds converted into SO42-, PO43-, NO3-, and CO2 under the extensive photocatalytic of them over Co3O4/MCM-41. The oxidizing species trapping test verified the controlling of the methyl parathion degradation pathway by the hydroxyl radicals. Finally, the composite showed significant reusability properties and applied five times in the oxidation of methyl parathion with considerable degradation percentages.


Assuntos
Cobalto , Metil Paration , Nanopartículas , Óxidos , Praguicidas , Dióxido de Silício , Purificação da Água , Água , Cobalto/química , Vidro/química , Metil Paration/química , Nanopartículas/química , Oxirredução , Óxidos/química , Praguicidas/química , Dióxido de Silício/química , Água/química , Purificação da Água/métodos
2.
J Agric Food Chem ; 68(6): 1645-1653, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31972072

RESUMO

This study investigated the toxicity of trichlorfon (TCF) to the freshwater algae Chlamydomonas reinhardtii, as well as its biodegradation and metabolic fate. The growth of C. reinhardtii decreased with increasing TCF concentration, and the maximum inhibition ratio was 51.3% at 200 mg L-1 TCF compared to the control. Analyses of pigment content, chlorophyll fluorescence, and antioxidant enzymes indicated that C. reinhardtii can produce resistance and acclimatize to the presence of TCF. The variations in pH during cultivation suggested that photosynthetic microalgae have innate advantages over bacteria and fungi in remediating TCF. A 100% biodegradation rate was achieved at a maximum concentration of 100 mg L-1 TCF. Ten metabolites were identified by GC-MS, and the degradation pathways of TCF by the algae were proposed. This research demonstrated that C. reinhardtii is highly tolerant to and can efficiently degrade TCF. Thus, C. reinhardtii can be used to remove traces of TCF from natural water environments and to treat TCF-contaminated wastewater.


Assuntos
Chlamydomonas reinhardtii/metabolismo , Praguicidas/metabolismo , Triclorfon/metabolismo , Biodegradação Ambiental , Cromatografia Gasosa-Espectrometria de Massas , Microalgas/metabolismo , Praguicidas/química , Praguicidas/toxicidade , Fotossíntese , Triclorfon/química , Triclorfon/toxicidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade
3.
J Agric Food Chem ; 68(3): 735-741, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31895559

RESUMO

Facile fabrication of difunctional nanoparticles (NPs) for pesticide delivery and imaging is still a fascinating challenge. Here, water-dispersible difunctional NPs were developed using flash nanoprecipitation (FNP) where self-assembling amphiphilic block copolymers were used to encapsulate a highly hydrophobic model pesticide, Lambda-cyhalothrin, and the fluorescent dye Nile red. The particle size (ranging from 158 to 280 nm) and fluorescence property of NPs could be controlled by varying the flow rate or Nile red feed concentration. The aggregation state and rearrangement of the dye molecules in the NPs were also investigated. IVIS imaging and confocal laser scanning microscopy analysis demonstrated that the resulting difunctional nanopesticide particles could allow accurate in situ tracking of the pesticide on the leaf surface, while effectively avoiding interference from chlorophyll autofluorescence. The difunctional NP suspension maintained high insecticidal activity and stability. This work demonstrates the feasibility and great potential of the FNP method in universal fabrication of multifunctional NPs with in situ pesticide tracing and crop protection capabilities.


Assuntos
Nanopartículas/química , Nitrilos/química , Imagem Óptica/métodos , Praguicidas/química , Piretrinas/química , Proteção de Cultivos , Fluorescência , Tamanho da Partícula , Folhas de Planta/química , Polietilenoglicóis/química
4.
Chemosphere ; 241: 125089, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629234

RESUMO

The Pantanal (Brazil) is a wetland region characterized by seasonal flooding. Hydrological cycles influence the water physicochemical parameters, causing seasonal variations in pH and nitrites. Thus, the objective of this study was to evaluate the effects of varying pH and nitrite concentrations on the toxicity of the cypermethrin-based pesticide Barrage®, considering both lethal (mortality) and sublethal endpoints (growth and development). Larvae of the endemic shrimp Macrobrachium pantanalense and of the estuarine Amazonian congener Macrobrachium amazonicum were exposed to cypermethrin (through Barrage®) under several pH levels (6.5, 7.5 and 8.5) or nitrite concentrations (0.1, 0.2 and 0.4 mg/L). The pH had direct effects on all the tested endpoints for both species. For M. pantanalense, the lethal effects of the cypermethrin formulation were more pronounced at low pH (96-h LC50 = 0.004 µg/L at pH 6.5, and 0.146 µg/L at pH 8.5). For M. amazonicum, an opposite response was observed, with increased toxicity of the formulation at high pH (96-h LC50 = 0.110 µg/L at pH 6.5 and 0.044 µg/L at pH 8.5). Variations in pH also seemed to modify the sublethal effects of the formulation on larval growth and development of M. pantanalense. Nitrite concentrations affected larval growth of both species, modifying also the effects of the cypermethrin formulation on the larval development of M. amazonicum. This work shows the importance of considering abiotic factors for risk assessment either due to possible direct effects on the physiology of organisms and/or due to interactions with other stressors, particularly in fragile biomes such as Pantanal.


Assuntos
Água Doce/química , Palaemonidae/efeitos dos fármacos , Praguicidas/toxicidade , Piretrinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Ecotoxicologia , Feminino , Água Doce/análise , Concentração de Íons de Hidrogênio , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Dose Letal Mediana , Mortalidade , Nitritos/análise , Nitritos/química , Palaemonidae/crescimento & desenvolvimento , Praguicidas/química , Piretrinas/química , Especificidade da Espécie , Testes de Toxicidade Aguda , Áreas Alagadas
5.
Chemistry ; 26(2): 390-395, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31596010

RESUMO

Dearomatisation of indole derivatives to the corresponding isatin derivatives has been achieved with the aid of visible light and oxygen. It should be noted that isatin derivatives are highly important for the synthesis of pharmaceuticals and bioactive compounds. Notably, this chemistry works excellently with N-protected and protection-free indoles. Additionally, this methodology can also be applied to dearomatise pyrrole derivatives to generate cyclic imides in a single step. Later this methodology was applied for the synthesis of four pharmaceuticals and a pesticide called dianthalexin B. Detailed mechanistic studies revealed the actual role of oxygen and photocatalyst.


Assuntos
Indóis/química , Luz , Praguicidas/química , Preparações Farmacêuticas/química , Pirróis/química , Catálise , Imidas/química , Praguicidas/síntese química , Preparações Farmacêuticas/síntese química
6.
J Sci Food Agric ; 100(4): 1653-1661, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31802493

RESUMO

BACKGROUND: The consumption of pesticide-contaminated sour cherries as fruit or juice has become a major health concern, and so the search for alternative processing technologies, such as pulsed electric fields (PEF), ozone (O), and ultrasonication (US) has intensified. The objectives of this experimental study of sour cherry juice were fourfold: (1) to quantify the removal efficiency of new processing technologies (PEF, O, US), and their combinations, for the pesticides chlorpyrifos ethyl, τ-fluvalinate, cyprodinil, pyraclostrobin, and malathion; (2) to detect their impact on physical, bioactive, and sensory properties; (3) to determine their microbial inactivation levels for Escherichia coli O157:H7, Bacillus cereus, Pseudomonas syringae subs. Syringae, and Penicillum expansum; and (4) to jointly optimize multiple responses of physical, quality, and sensory properties, pesticides, and microbial inactivation. RESULTS: Except for all the O treatments, the physical, bioactive and sensory properties of sour cherry juice were not adversely affected by the treatments. The joint optimization suggested PEF1 (24.7 kV cm-1 for 327 µs), PEF2 (24.7 kV cm-1 for 655 µs), PEF2 + O + US, US, and PEF2 + O as the five best treatments. PEF2 + O + US best achieved both pesticide removal and microbial inactivation. CONCLUSION: PEF2 + O + US provided promising reductions in pesticide and microbial loads. © 2019 Society of Chemical Industry.


Assuntos
Manipulação de Alimentos/métodos , Sucos de Frutas e Vegetais/microbiologia , Praguicidas/química , Prunus avium/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Manipulação de Alimentos/instrumentação , Sucos de Frutas e Vegetais/análise , Viabilidade Microbiana , Praguicidas/isolamento & purificação , Prunus avium/química , Controle de Qualidade
7.
Environ Pollut ; 256: 113372, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31672361

RESUMO

In this study, a weather-based multicomponent model was developed based on the unique biostructures and metabolic processes of mushrooms to evaluate their uptake of pesticides from soils, and the effects of temperature and relative humidity on the bioaccumulation of pesticides in mushrooms was comprehensively quantified. Additionally, a new pseudo-partition coefficient between mushrooms and soils was introduced to assess the impacts of different physiochemical properties on the pesticide uptake process. The results indicate that, in general, the pseudo-partition coefficient increases as the relative humidity increases for both the air and soil according to Fick's law of gas diffusion and the spatial competition of molecules, respectively. Meanwhile, the effect of temperature on the pesticide bioaccumulation process is more complex. For most pesticides (e.g., atrazine), the pseudo-partition coefficient that was computed from the transpiration component had a maximum value at a specific temperature due to the temperature dependency of the transpiration and biodegradation processes. For some pesticides (e.g., ethoprophos), the pseudo-partition coefficient of the air-deposition component had a maximum value at a certain temperature that was caused by the ratio of the soil-air internal transfer energy and degradation activation energy of the pesticide. It was also concluded that for relatively low-volatility pesticides, transpiration dominated the bioaccumulation process; this was mainly determined from the pesticide water solubility. For nonbiodegradable pesticides (e.g., lindane), the computed coefficient values were relatively low due to their insolubility in water, which inhibits bioaccumulation in mushrooms and is one of the main reasons for their long-term persistence in soils.


Assuntos
Agaricales/química , Modelos Biológicos , Praguicidas/análise , Poluentes do Solo/análise , Solo/química , Tempo (Meteorologia) , Agaricales/metabolismo , Bioacumulação , Biodegradação Ambiental , Difusão , Praguicidas/química , Poluentes do Solo/química , Solubilidade , Temperatura Ambiente , Volatilização
8.
Chemosphere ; 238: 124550, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31425868

RESUMO

Large volumes of contaminated water are produced via intentional and unintentional incidents, including terrorist attacks, natural disasters and accidental spills. Contaminated waters could contain harmful chemicals, which present management and disposal challenges. This study investigates three Advanced Oxidation Processes (AOPs) - UV/H2O2, O3/H2O2, and electrochemical oxidation using a boron-doped diamond (BDD) anode - to treat eleven contaminants including herbicides, pesticides, pharmaceuticals, and flame retardant compounds. To address treatment and toxicity concerns, this study focuses on the resulting microbial toxicity via Microtox® toxicity and Nitrification Inhibition tests. The results suggest four functional Microtox® toxicity categories upon AOP treatment, which are useful for streamlining AOP selection for specific applications. Except for one compound, the O3/H2O2 and UV/H2O2 AOPs achieved, within experimental error, 100% parent compound degradation during 2 h of treatment for all contaminants, as well as Microtox® toxicities that declined below 10% by the end of the treatment. In addition, anodic oxidation with a BDD electrode exhibited slower degradation and some increases in Microtox® toxicity. Only one compound exhibited above 50% Nitrification Inhibition, indicating the robustness of activated sludge to many contaminated and AOP-treated waters. These results indicate that AOP pre-treatment can be a viable strategy to facilitate drain disposal of contaminated waters, but that eco-toxicity may remain a concern.


Assuntos
Reatores Biológicos , Diamante/química , Eletrodos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Poluição da Água/análise , Boro/química , Herbicidas/análise , Herbicidas/química , Herbicidas/toxicidade , Peróxido de Hidrogênio/química , Oxirredução , Praguicidas/análise , Praguicidas/química , Praguicidas/toxicidade , Microbiologia da Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
9.
SAR QSAR Environ Res ; 31(1): 49-72, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31766890

RESUMO

In Europe, agencies and official organizations involved in the pesticide control such as the EFSA, ECHA, JRC and ECETOC or even the OECD are pointing out that the software tools based on quantitative structure relationship models, i.e. QSAR and QSPR, have a huge potential to improve the pesticide risk assessment process. In this sense, these non-animal test methods can promote the competitiveness of agriculture in this region: the consumer safety is increased with them due to the possibility of perform an overall better risk assessment of the degradation products and metabolites from pesticides. However, the use of theses computational-based (in silico) tools must be much more systematised and harmonised, improving their validation and including case studies to test them. To open databases, incorporating critical data in an orderly manner for building the models, becomes also necessary. Moreover, quantum chemistry through the Density Functional Theory should be promoted as tool for calculation of quantum descriptors, especially for the study of similar compounds with the same carbon skeleton but differing substitution patterns, e.g. isomers.


Assuntos
Modelos Químicos , Praguicidas/química , Relação Quantitativa Estrutura-Atividade , Medição de Risco/métodos , União Europeia , Modelos Moleculares , Teoria Quântica
10.
Environ Sci Process Impacts ; 22(1): 84-94, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31848545

RESUMO

In this work, the stability and aggregation behaviour of CeO2 nanoparticles (NPs) was investigated to predict their fate in the agricultural environment. For this, the aggregation kinetics of CeO2 NPs was studied under varying pH, ionic strength (IS), dissolved organic matter (DOM) and carbonate concentrations in the presence of clay. Furthermore, different types of irrigation water have been used to check the fate of CeO2 nanoparticles (NPs) in complex aqueous matrices. The results show that critical coagulation concentration (CCC) values obtained for CeO2 NPs, i.e. 26.5 mM and 7.9 mM for NaCl and CaCl2 respectively, drastically decreased to 16.2 mM and 1.87 mM in the presence of bentonite clay colloids, which may lead to their deposition within the soil matrix. However, the presence of bicarbonate ions (0.1-2 mM) along with DOM (1-20 mg L-1) may result in their stabilization and co-transport of CeO2 NPs with clay in water bodies having low ionic strength. It was also observed that the negative charge of a bentonite clay suspension was completely reversed with an increase in CeO2 concentration by 37.5 times. The critical charge reversal concentration value was 284.4 mg L-1 in Milli-Q water whereas values were observed to be 680 mg L-1 in synthetic-soft water, followed by natural river water (867 mg L-1) and synthetic-hard water (910 mg L-1). The synergistic effect of temperature and ionic strength was observed on the aggregation behaviour of CeO2 NPs in environmental water samples of varying composition.


Assuntos
Irrigação Agrícola , Cério , Nanopartículas , Praguicidas , Argila , Coloides , Nanopartículas/química , Concentração Osmolar , Praguicidas/química , Água
11.
Chemosphere ; 240: 124912, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574437

RESUMO

In this work, the combination of biological and electrochemical processes to mineralize oxyfluorfen has been studied. First, an acclimatized mixed-culture biological treatment was used to degrade the biodegradable fraction of the pesticide, reaching up to 90% removal. After that, the non-biodegraded fraction was oxidised by electrolysis using boron-doped diamond as the anode. The results showed that the electrochemical technique was able to completely mineralize the residual pollutants. The study of the influence of the supporting electrolyte on the electrochemical process showed that the trace mineral solution used in the biological treatment was enough to completely mineralize the oxyfluorfen, resulting in total organic carbon removal rates that were well-fitted by a first-order model with a kinetic constant of 0.91 h-1. However, the first-order degradation rate increased approximately 20% when Na2SO4 was added as supporting electrolyte, reaching a degradation rate of 1.16 h-1 with a power consumption that was approximately 70% lower.


Assuntos
Eletrólise/métodos , Éteres Difenil Halogenados/química , Éteres Difenil Halogenados/metabolismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Reatores Biológicos/microbiologia , Boro , Diamante , Eletrodos , Eletrólise/instrumentação , Cinética , Oxirredução , Praguicidas/química , Praguicidas/metabolismo , Sulfatos/química , Eliminação de Resíduos Líquidos/métodos
12.
Food Chem ; 307: 125534, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31644980

RESUMO

There has been increasing recent concern about the agricultural use of organophosphorus pesticides. A rapid and sensitive fluorescence assay for the detection of three organophosphorus pesticides has therefore been developed using 6-carboxy-fluorescein labeling aptamer as the probe and functionalized magnetic nanoparticles as the separation carrier. The aptamer hybridized with complementary DNA conjugated on the surface of the magnetic nanoparticles to form a magnetic aptamer-complementary DNA complex. Upon introducing the target organophosphorus pesticide, the aptamer departed from the complementary DNA, resulting in the fluorescence signal. Under optimized conditions, the limits of detection (LODs, S/N = 3) for trichlorfon, glyphosate, and malathion were 72.20 ng L-1, 88.80 ng L-1, and 195.37 ng L-1, respectively. The method was applied for the detection of trichlorfon, glyphosate, and malathion in spiked lettuce and carrot samples. The recoveries were in the range of 79.4%-118.7%, which were in good agreement with those obtained by gas chromatography, and the relative standard deviations were also acceptable. The method therefore has high sensitivity, so provides a means for the detection of multiple organophosphorus pesticides.


Assuntos
Aptâmeros de Nucleotídeos/química , Nanopartículas , Compostos Organofosforados/análise , Praguicidas/análise , Espectrometria de Fluorescência , Cromatografia Gasosa , Daucus carota/química , Corantes Fluorescentes , Glicina/análogos & derivados , Glicina/análise , Alface/química , Limite de Detecção , Magnetismo , Malation/análise , Praguicidas/química , Triclorfon/análise
13.
J Agric Food Chem ; 68(2): 461-470, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31868356

RESUMO

Contamination of the environment by toxic pesticides has become of great concern in agricultural countries. Chlorpyrifos (CP) is among the pesticides most commonly detected in the environment owing to its wide agricultural applications. The aim of this study was to compare potential changes in the toxicity of CP after irradiation. To this end, photolysis of CP was conducted under simulated sunlight, and neurotoxicity assessment was carried out at CP of 20 and 50 µg L-1 and its corresponding irradiated mixture solutions which contain a mixture of identified intermediates using the nematode, Caenorhabditis elegans as a model organism. Photodegradation of 20 µg L-1 CP for 1 h produced no obvious reduction of physiological damage, and more serious effects on animal movement were detected after exposure of the animals to a solution of 50 µg L-1 for 1 h irradiation compared with unirradiated solution. GABAergic and cholinergic neurons were selectively vulnerable to CP exposure, and maximal neuropathological alterations were observed after 1 h irradiation of the CP solutions in coherence with the behavioral impairment. The generation of photoproducts was considered to be responsible for the enhanced disturbance on those biological processes. This work provided useful information on the toxicological assessments of chemicals that were produced during the environmental transformation of pesticides.


Assuntos
Caenorhabditis elegans/efeitos dos fármacos , Clorpirifos/toxicidade , Neurônios/efeitos dos fármacos , Praguicidas/toxicidade , Animais , Comportamento Animal/efeitos dos fármacos , Caenorhabditis elegans/fisiologia , Clorpirifos/química , Clorpirifos/efeitos da radiação , Feminino , Masculino , Estrutura Molecular , Praguicidas/química , Praguicidas/efeitos da radiação , Fotólise , Luz Solar
14.
Ecotoxicol Environ Saf ; 190: 110067, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855788

RESUMO

Earthworm provides sustainability towards the agroecosystem which can be degraded day by day by the extensive use of pesticides (e.g., fungicides, insecticides and herbicides). The present study attempts to develop a predictive quantitative structure-activity relationship (QSAR) model for toxicity of pesticides to earthworm in order to give a suitable guidance for designing new analogues with lower toxicity by exploring the important chemical features which are required to develop safer alternatives. The QSAR model was developed by using the negative logarithm of lethal concentration (pLC50) values of pesticides towards earthworm. We have used various 2D descriptors along with extended topochemical atom (ETA) indices as independent variables for the development of the model. The developed partial least squares (PLS) model was subjected to statistical validation tests proving that the model is statistically reliable and robust (R2 = 0.765, Q2 = 0.614, Q2F1 = 0.734, Q2F2 = 0.713). The contributing descriptors in the model suggested that the pesticides may affect the earthworm nucleic acid through various physicochemical interactions including hydrophobicity, hydrogen bonding, electron donor acceptor complex formation, π-π stacking interaction and charge transfer complex formation.


Assuntos
Oligoquetos/efeitos dos fármacos , Praguicidas/toxicidade , Animais , Ligações de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Análise dos Mínimos Quadrados , Praguicidas/química , Relação Quantitativa Estrutura-Atividade
15.
J Agric Food Chem ; 67(49): 13550-13557, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31721576

RESUMO

Enantioselectivity is usually ignored when assessing potential biochar-based methods of redressing pesticide contamination of soils. In this study, the effect of woodchip biochar (WBC) on the enantioselective dissipation of metalaxyl in soil and its uptake and translocation by lettuce were investigated. S-metalaxyl (T1/2 = 29.8 days) dissipated more quickly than R-metalaxyl (T1/2 = 36.4 days) in unamended soil. The addition of WBC to the soil decreased the dissipation rate and the enantioselectivity of metalaxyl. Metalaxyl distribution showed opposing enantioselectivity in lettuce, with roots and shoots showing preferences for R-metalaxyl and S-metalaxyl, respectively. Enrichment with WBC decreased the concentrations of metalaxyl and metalaxyl acid enantiomers in lettuce and reduced the ability of the shoots to transport the highly toxic R-metalaxyl from roots. This is the first study to provide evidence that amending soil with biochar affects the enantioselective uptake and translocation of a chiral pesticide.


Assuntos
Alanina/análogos & derivados , Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Alface/metabolismo , Praguicidas/química , Poluentes do Solo/química , Adsorção , Alanina/química , Alanina/metabolismo , Biodegradação Ambiental , Recuperação e Remediação Ambiental/instrumentação , Praguicidas/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Poluentes do Solo/metabolismo
16.
J Agric Food Chem ; 67(49): 13518-13525, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31757125

RESUMO

Coordinating unsaturated metal sites (CUS) on the surface of metal-organic frameworks (MOFs) could be used to adsorb His-tagged proteins. The specific adsorption between CUS and His-tagged proteins could reduce preparation steps, shorten preparation time, and could also avoid the binding between the metal ion of metalloenzyme active center and the chelating agent to ensure the enzyme activity. In this study, MIL-88A was synthesized by hydrothermal method and used to purify and immobilize His-tagged organophosphohydrolase (OpdA) in one step for organophosphate bioremediation. Under optimized conditions, OpdA@MIL-88A had a maximal activity of 1554 U/gprotein, which was nearly 5 times higher than free OpdA. Compared with free OpdA, OpdA@MIL-88A exhibited improved organic solvent tolerance, SDS tolerance, thermal stability, and storage stability. OpdA@MIL-88A was used to degrade organophosphorus pesticides on grapes and cucumbers. After reuse 6 times, OpdA@MIL-88A retained more than 66% and 61% of the initial activity, respectively. Therefore, this proposed strategy provided a facile and effective method for degradation of organophosphorus pesticides.


Assuntos
Agrobacterium tumefaciens/enzimologia , Proteínas de Bactérias/metabolismo , Estruturas Metalorgânicas/química , Compostos Organofosforados/metabolismo , Praguicidas/metabolismo , Monoéster Fosfórico Hidrolases/química , Agrobacterium tumefaciens/genética , Agrobacterium tumefaciens/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Biodegradação Ambiental , Meios de Cultura/química , Meios de Cultura/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/genética , Enzimas Imobilizadas/metabolismo , Compostos Organofosforados/química , Praguicidas/química , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/metabolismo
17.
Environ Sci Pollut Res Int ; 26(32): 33631-33641, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31587166

RESUMO

Pesticides are highly hazardous chemicals for the environment and human health and their use in agriculture is constantly increasing. Although 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane 4,4'-DDT was banned at developed countries, it is still one of the most dangerous of chemical due to accumulation in the environment. It is known that the toxicity of DDT affects some enzyme systems biochemically. The main motivation of this study is to develop an effective adsorbate for the removal DDT, which was chosen as a model hydrophobic pesticide, out of aqueous systems. For this purpose, the bare diatomite particles were magnetically modified and a hydrophobic ligand attached to enhance its adsorptive and physio-chemical features. Under optimal conditions, a high adsorption capacity, around 120 mg/g with the hydrophobic and magnetic diatomite particles, modification of the diatomite particles reduced average pores diameter whereas surface area and total pore volume increased (around 15-folds). After five consecutive adsorption-desorption cycles, no significant decrease in adsorption capability was observed. The adsorption isotherms (Langmuir, Freundlich, and Flory-Huggins) applied to the data indicated that the adsorption process occurred via monolayer adsorption in an entropy-driven manner. The kinetic data also revealed the quick adsorption process without any diffusion limitations. Graphical Abstract.


Assuntos
Terra de Diatomáceas/química , Praguicidas/química , Poluentes Químicos da Água/química , Adsorção , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Fenômenos Magnéticos , Praguicidas/análise , Água , Poluentes Químicos da Água/análise , Purificação da Água
18.
SAR QSAR Environ Res ; 30(11): 825-846, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31607178

RESUMO

We developed models for predicting fish early-life stage (ELS) toxicities oriented to industrial chemicals. The training set was constructed without data from the Office of Pesticide Programs Pesticide Ecotoxicity Database, the main source for the pesticide-biased training set used in our previous work (SAR QSAR Environ. Res. 29:9, 725-742). In addition to the descriptors from the previous study, we also used water solubility to develop the new models, which were evaluated against the test set used in our previous study so that we could focus on the effects of the different training set and the additional descriptor. The statistics for the new models were hardly better than those for the previous models, which suggests, contrary to our expectations, that pesticide-biased data can successfully be used to develop models for predicting the fish ELS toxicities oriented to industrial chemicals. Acute Daphnia magna toxicity was important for the predictive QSAARs in both studies. A distance-based method for defining the applicability domains indicated that water solubility was a key indicator for detecting underestimated chemicals. The comparison of fish ELS toxicities for chemicals presented in different literatures revealed the uncertainty of the experimental data, which may lead to the low predictivity.


Assuntos
Daphnia/efeitos dos fármacos , Modelos Biológicos , Praguicidas/toxicidade , Relação Quantitativa Estrutura-Atividade , Poluentes Químicos da Água/toxicidade , Alternativas aos Testes com Animais , Animais , Daphnia/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Praguicidas/química , Testes de Toxicidade Aguda , Poluentes Químicos da Água/química
19.
SAR QSAR Environ Res ; 30(12): 865-878, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31595789

RESUMO

DNA methylations are carried out by DNA methyltransferases (DNMTs) that are key enzymes during gene expression. Many chemicals, including pesticides, have shown modulation of epigenetic functions by inhibiting DNMTs. In this work, human DNMTs were evaluated as a potential target for pesticides through virtual screening of 1038 pesticides on DNMT1 (3SWR) and DNMT3A (2QRV). Molecular docking calculations for DNMTs-pesticide complexes were performed using AutoDock Vina. Binding-affinity values and contact patterns were employed as selection criteria of pesticides as virtual hits for DNMTs. The best three DNMT-pesticides complexes selected according to their high absolute affinity values (kcal/mol), for both DNMT1 and DNMT3A, were flocoumafen (-12.5; -9.9), brodifacoum (-12.4; -8.4) and difenacoum (-12.1; -8.7). These chemicals belong to second-generation rodenticides. The most frequent predicted interacting residues for DNMT1-pesticide complexes were Trp1170A, Phe1145A, Asn1578A, Arg1574A and Pro1225A; whereas for DNMT3A those were Arg271B, Lys740A, and Glu303B. These results suggest that rodenticides used for pest control are potential DNMT ligands and therefore, may modulate DNA methylations. This finding has important environmental and clinical implications, as epigenetic pathways are critical in many biochemical processes leading to diseases.


Assuntos
DNA (Citosina-5-)-Metiltransferase 1/química , DNA (Citosina-5-)-Metiltransferases/química , Inibidores Enzimáticos/química , Metiltransferases/metabolismo , Praguicidas/química , 4-Hidroxicumarinas/química , Simulação por Computador , Metilação de DNA , Bases de Dados de Compostos Químicos , Humanos , Simulação de Acoplamento Molecular , Relação Quantitativa Estrutura-Atividade , Reprodutibilidade dos Testes
20.
Chemosphere ; 237: 124551, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549662

RESUMO

To characterize the potential endocrine-disrupting chemicals (EDCs) in the environment that interact with the crustacean ecdysone receptor (EcR), we established a method involving in silico modeling/molecular docking and in vitro reporter gene assay. Cherry shrimp (Neocaridina davidi) EcR (NdEcR) and retinoid X receptor (NdRxR) were identified and cloned for use in this method. A theoretical 3D model of NdEcR ligand-binding domain (LBD) was built in silico based on sequence homology with the established X-ray structure of insect EcR. The interaction of the NdEcR LBD with ecdysteroids, diacylhydrazine (DAH) pesticides, and other potential EDCs was evaluated using molecular docking programs. The results revealed that the ligand-binding pocket in the NdEcR LBD was flexible and adaptive for accommodating ligands of different shapes. The agonistic and antagonistic activities of the candidate compounds were further assessed by in vitro reporter gene assay using human cell lines transiently transfected with NdEcR and NdRxR expression plasmids and a reporter plasmid containing synthesized ecdysone response element. The assay was validated by the dose-dependent responses of EcR-mediated gene transcription after treating the transfected cell lines with ecdysteroids, 20-hydroxyecdysone, and ponasterone A. Examination of the candidate compounds using the reporter gene assay revealed restricted functional specificity to ecdysteroids and DAHs. Three of the tested DAH pesticides originally targeting the insect EcR were found to be weak agonists and strong antagonists of NdEcR. These results suggest that DAHs are potential EDCs for crustaceans that disrupt their ecdysteroid signals by functioning as EcR agonists or antagonists.


Assuntos
Crustáceos/efeitos dos fármacos , Ecdisteroides/farmacologia , Praguicidas/toxicidade , Receptores de Esteroides/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Simulação por Computador , Crustáceos/metabolismo , Ecdisona/metabolismo , Ecdisona/farmacologia , Ecdisteroides/toxicidade , Ecdisterona/análogos & derivados , Ecdisterona/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Genes Reporter , Humanos , Simulação de Acoplamento Molecular , Praguicidas/química , Praguicidas/metabolismo , Filogenia , Receptores de Esteroides/agonistas , Receptores de Esteroides/antagonistas & inibidores , Receptores de Esteroides/genética , Receptores X Retinoide/química , Receptores X Retinoide/genética , Receptores X Retinoide/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA